"Jeff Morris" wrote in message
...
wrote:
Having read the responses to and comments on my original post, I am
still left with a few questions:
If I am on the Bahama Bank or in the Bahamian Exumas or in Hawk Channel
off Key Largo or in a bay or "river" or "creek" off the Chesapeake Bay,
negotiating shoals on a cloudy and windy day and GPS goes out because
it was suddenly turned off, is that not an "end" for me?
Yes. I suggest you stay off the water. Those of us who know how to
navigate without GPS will thank you.
Does anyone believe or expect GPS to be turned off only for a few
minutes or hours? I would expect weeks to months, or longer, of "ended"
signals.
Actually, its most likely it will be degraded in some locality. It can be
made useless for terrorists by degrading the altitude component.
And mo Would anyone want to be in a commercial or private airplane
when making an initial approach in low ceiling weather to landing and
having GPS suddenly go off? This may well be an "end."
Commercial flights do not rely on GPS for approaches.
There are certain procedures available with GPS that are impractical (or
even undoable) for other navigation techniques. For instance I have made
dark and stormy approaches to a couple of harbors that I would not have done
without GPS and radar. These are comfortable with GPS with radar as a
backup and sometimes a calibrator. I would not attempt these by radar
alone.
Note that lights and other aids to navigation are being retired. In a few
years it will be impractical to sail a lot of places without GPS.
Aircraft use of GPS provides very quick problem detection. Implemented in
WAAS it provides an indication of non-proper operation in seconds.
Commercial airplanes certainly fly GPS approaches. I don't think there are
any precision approaches flown GPS yet...but non-precision approaches
certainly are. Eventually it is likely that the VOR/DME system and the ILS
will give way to GPS.
We are busily embedding GPS into the fabric of society. It is very
unlikely that the gov. will suspend the system at all...if they must it
will likely be for rather short periods of time.
Jim Donohue